Apparatus for mixing and feeding pulverized fuel



y 1929. E. H. ELZEMEYER ET AL 1,721,439

APPARATUS FOR MIXING AND FEEDING PULVERIZED FUEL Filed June 28, 1923 /5 My '4 Erwin/is: "I [Zw S/M hwwe g v flea)" flzzamgya- Patented July 16, 1929.

UNITE ures j T E N y F! C E.

sRnsT n. ELZEMEYEB AND PAUL s. KNITTEL, on ST. nouisnlssonni; innie sL'zE MEYER EXECUTRIX or SAID ERNST H. ELZEMEYER, DECEASED. p

APPARATUS FOR; MIXING ANnTnEnING rULv RIzEnTUnL."

Application filed June 28,

This invention relates to apparatus for producing and mixing fine fuel with air to form a combustible mixture and. for introducing such mixture into the combustion chamber of a furnace to be burned in suspension therein.

The'principal object of the present invention is to increase the efliciency of the combustible mixture by securing a mantleof air around each individual particle of fuel and an even distribution of the mixture over the full width of the burner opening. Other objects are simplicity and cheapness of construction and compactness of design. The inventlon consists in the construction, arrangement and combinations of parts hereinafter described and claimed.

In the accompanying drawing, which forms part of this specification and wherein like symbols refer to like parts wherever they occur,

Fig. 1 isa plan view of our pulverized fuel mixingand feeding apparatus shown in connection with a pulverizing device and the combustion chamber of a furnace;

Fig. 2 is a side elevation of the apparatus shown in Fig. 1; I

Fig. 3 is an enlarged detail longitudinal sectional view of the mixing burner or nozzle; and

Fig. 4 is a bottom plan view of said burner or nozzle.

Referring to the accompanying drawing, our apparatus is shown in connect-ion with a suitable pulverizing device 4, wherein the fuel, such as coal, is comminuted preferably to a powder, and with the combustion chamber 5 of a furnace, wherein the pulverized coal is burned. The pulverizing device 4 is of the rotary ring type and comprises a casing having a rotary carrier 4; therein upon which are supported the grinding rings 1". The pulverizer 4 has a feed hopper 6 adapted to receive the material that is to be pulverized; and it is also provided with an outlet 7 through which the pulverized material is withdrawn from the pulverizer. The pulverizer outlet 7 opens into the lower end of a suitable separating and mixing chamber 8 preferably of the kind shown in our Patent No. 1,449,169, dated March 20, 1923, wherein the fine particles of coal are separated from the heavier particles and mixed with air. The pulverizing device, the furnace combustion chamber, and the separating and 1922. Serial No. 648,402.

mixing chamber maybe-of any-desired construction and it is considered unnecessary to illustrate these devices in detail. 7 r

The presentfuel mixing and feeding apparatuscomprises two or' more suitably proportioned fan-blowers 10 mounted on a platform 11, which is supported immediately a above the separating and mixing chamber 8 by means of a suitable framework-12.- The fan blowers 1O areof the same size andpressure and are both driven at thesame rate of' speed by means of an electric motor 13, which ismountedon the supporting :platform 11 between said fan-blowers; Sepa' rate intake pipes or conduits l l le'ad from the upper end of the separatingchamber 8 to the inlet of each of the" fan-blowers which furnish thesuction necessary to remove'the fine fuel from said separating chamber. These conduits are provided withair inlet valves 14:, whereby the amount of'air in the mixture can be regulated to obtain either a reducing flame or an oxidizingflame. Separate discharge pipes or conduits 15 lead from the discharge oroutlet of-each"fan-' blower to theupper end of a mixing burner- 16, whereby fuel drawn into said'fan-blowers from the pulverizer is delivered to said burner by separate blasts of air.

The burner 16 is preferably mounted on the top of the combustion chamber 5; and the lower end portion of said burner extends downwardly into said chamber through an opening provided in the top wall thereof. The upper portion of the burner is in the form of a hopper or chamber 17 having downwardly converging side walls; and the cross-sectional area of said hopper or chamber portion of said burner is greater than the combined cross-sectional area of boththe discharge conduits 16 that communicate therewith. The lower end or nozzle portion of the burner is preferably of oval crosssection and of greater cross-sectional area than the combined cross-sectional area of both of the discharge or delivery pipes or conduits 15.

The operation of the apparatus is as follows:

Fuel, preferably coal, is fed into the pulverizing device 4 through the feed hopper 6 thereof and is pulverized by the rotary elements of said device. The suction created by the fan-blowers 10 causes the pulverized material to be drawn through the outlet 7 of the pulverizer into the separating chamber 8. This expansion or separating chamber, by reason of its larger area, has the effect of decreasin the velocity of the air currents produced by the suction of the fan-blowers, thereby causing the heavier particles to fall back into the pulverizing device. The fine particles are then drawn upwardly through the intake pipes 14 into the fan-blowers and delivered thereby through the discharge pipes 15 into the expansion or mixing chamber 17 of the burner 16 by blasts of air created by said fan-blowers.

The pressure of the air blasts and the amount of fine fuel delivered thereby to the hopper or mixing chamber 17 of the burner 16 are the same in each of the delivery pipes 15. The two streams of air and fine fuel upon entering the hopper 17 of the burner 16 are deflected toward each other by the inclined Walls of the hopper and are thus conjoined together. The union of the two streams is further facilitated by reason of'the larger area of the expansion chamber 17, which has the effect of reducing the velocity of the air blasts created by the fans, and also by'reason of the fact that the pressure of such air blasts is low enough so that the draft existing in the furnace has the effect of creating in said expansion chamber and the portions of the delivery pipes 15 adjacent thereto, a pressure that is less than atmospheric pressure. The combustible mixture thus produced is then drawn through the nozzle portion of the burner into the combustion chamber of the furnace and burned in suspension therein.

It is obvious from the foregoing descrip* tion that our apparatus is very simplein construction, that it can be cheaply manufactured and easily assembled, that it secures a uniform mixture of air and fine fuel of the proportion required to produce a com-- bustible mixture of maximum efiiciency, and that the advantage resulting from its use is very marked.

It is evident that changes may be made without departing from our invention and we do not wish to be limited to the precise construction shown and described. a For in stance, the pulverizing device, the separating chamber and the furnace combustion chamber may be of any desired construction, and

the apparatus may be adapted for use with fluid fuels as well as solid fuels.

What we claim is:

vAn apparatus of the kind described comprising a furnace, a fuel separating chamher, a burner having a mixing chamber and a nozzle portion communicating with said furnace, a plurality of conduits of substantially the same cross sectional area leading conduits.

Signed at St. Louis, Missournthis 23rd f day of June, 1923. y

ERNST H. E-LZEMEYER. PAUL S. ITTEL. 

